The present invention relates to the enhancement of manufacturing flow. In particular, the present invention relates to an automated method for determining a bin size or a number of bins in a flow manufacturing environment.
In many manufacturing operations, efficient manufacturing is critical to the operation, and thus profitability, of a company. It is important to have an adequate supply of product to the end customer, and it is also important to have as little inventory as possible in the manufacturing facility. In the manufacturing process itself, it is highly beneficial to keep the amount of work-in-progress (WIP) to a minimum. The lower amount of WIP results in more efficient manufacturing by helping reduce the amount of inventory which is tied up in a manufacturing line, and also to help the flow of the manufacturing operation by not having a large amount of WIP sitting idle at any particular manufacturing step. Reduced WIP also results in reduced costs associated with the inventory that is being manufactured, as well as helps reduce the overall cycle time of an operation.
However, it is also important that any particular process step in the manufacturing line does not run out of material to process. If a process step runs out of material to process, the process step may remain idle for a period of time, thus decreasing the efficiency of the entire manufacturing operation. Furthermore, it is often common in a manufacturing operation to have a specific process or manufacturing step which is a bottleneck. That is, the remaining processes or manufacturing steps within the manufacturing operation operate faster, or have a higher production rate, than the bottleneck step. Thus, the overall output of the manufacturing operation is limited by the bottleneck. Accordingly, if a bottleneck operation is idle, the total output of the manufacturing operation may be reduced. As a result, it is common for an operation to also have a certain amount of xe2x80x9csafety stock,xe2x80x9d which may be used to help ensure that manufacturing steps do not become idle as a result of normal variances in other steps within the manufacturing operation.
In many flow manufacturing operations, a xe2x80x9ckanbanxe2x80x9d type system is employed. In a kanban system, as is known in the art, a consumer pulls raw material from a producer. The producer does not produce material until given a command to do so by the consumer. In a kanban model, inventory is placed in bins, and each bin has an associated card. When a consumer depletes the inventory in a bin, the consumer returns the card to the producer. When the producer receives the card, it produces enough material to fill the bin. Accordingly, a producer only produces based on a demand from the consumer.
Traditionally, the size of a bin, and the number of bins used between a supplier and consumer, has been set according to empirical data associated with the operations, or by trial and error. Unfortunately, empirical data may not be available for a new or modified operation, thus leaving a period where the manufacturing operation may not be operating as efficiently as may be possible, having either too much or too little WIP present at the operation. Likewise, with a trial and error technique, the manufacturing operation may not be as efficient as possible. As discussed above, it is always advantageous to have a manufacturing operation which operates efficiently, and with a relatively low WIP level. Furthermore, in an established operation, an empirically chosen bin size and number may provide an adequate WIP level. In such a case, it may be desirable to know how much of the inventory is needed by the Kanban system to run efficiently, and how much of the inventory is needed to handle manufacturing process variances. Given such information, user may decide if it is worthwhile to attempt to improve the system by removing variances or by improving performance.
Therefore, it would be highly desirable to provide a new system and methodology for determining the size and/or number of bins to be used in a kanban system. In particular, it would be desirable to provide a system that allowed a user to specify a bin size, and would determine the number of bins which would be efficient for the operation. Furthermore, it would be desirable to provide such a system that allowed a user to specify the number of bins to be used, and would determine an enhanced bin size. In addition, it would be desirable to provide such a system that allowed a user to enhance the efficiency of a manufacturing operation while leaving an adequate safety margin should the manufacturing operation have unexpected variation in demand.
It is thus one aspect of the present invention to provide an improved method for determining a quantity of bins, or a bin size used in a manufacturing process having relatively constant production and consumption rates to keep inventory at a minimum while optimizing output.
It is a further aspect of the present invention to provide a method for enhancing efficiency of a manufacturing operation based on variable demand and supply, the method comprising the steps of:
selecting a number of bins for transferring material between a supplier and a consumer;
determining a production rate of said supplier and a consumption rate of said consumer;
determining a delivery time for delivering a bin from said supplier to said consumer;
determining a signal time for notifying said supplier that said consumer requires another filled bin; and
determining an amount of material to include in each bin based on a relationship between said consumption rate, said production rate, said delivery time, said signal time, and said number of bins.
It is still a further aspect of the present invention to provide a method for enhancing efficiency of a manufacturing operation based on variable demand and supply, the method comprising the steps of:
selecting an amount of material to include in an order, said order indicating that material is to be transferred from a supplier to a consumer;
determining a consumption rate of said consumer;
determining a production lead time based on the amount of time between placing said order by said consumer and receiving a completed order;
determining a total number of orders present between said supplier and said consumer based on a relationship between said consumption rate, said production lead time, and said amount of material to be included in an order.